Control system for dynamo-electric machines



June 22 192 6.

E. F. BLISS V CONTROL SYSTEM FOR DYNAMO ELECTRIC MACHINES Filed May 15,1924 Inventor:

- EImerITBIiSS,

His Attorney Patented June 22, 1926.

UNITED STATES PATENT OFFICE.

ELMER F. BLISS, 0F ALPLAUS, NEW YORK. ASSIGNOR T0 GENERAL ELECTRIC COM-PANY, A CORPORATION OF NEW YORK.

CONTROL SYSTEM FOR DYNAMIC-ELECTRIC MACHINES.

Application filed May 15, 1924.

My invention relates to control systems for dynamo electric machines andparticularly to control systems for balancer sets which are arranged tosupply the intermediate circuits of multi-voltage direct currentsystems.

One object of my invention is to provide an arrangement whereby undercertain predetermined conditions a balancer set is adapted automaticallyto be started and connected to a multi-voltage load circuit for thepurpose of supplying energy thereto.

Another object of my invention is to provide an arrangement wherebyanother balancer is automatically started and connected to themulti-voltage load circuit it the starting operation of a balancer setis not completed within a predetermined time.

Another object of my invention is to provide an arrangement forautomatically shutting down a balancer set when it fails white inservice and for automatically starting up another balancer set andconnecting it to the multi-voltage load circuit to take the place of thedisabled set.

Multi-voltage systems are used to some extent in electric elevatorsystems. In such systems it is very desirable that when a balancer setbecomes disabled, while in operation, the supply circuit should bedisconnected trom the load circuit as soon as possible and the balancerset should remain connected to the multi-voltage circuit until thevoltage of the load circuit has deased below a predetermined value. Thethe elevator motors are thus maintained after the supply circuit isdisconnected so that the elevator motors can teed into each other andinto the different units of the balancer sets, thus preventing thespeeds oi the individual elevators from becoming excessive and effectingthe operation of their overspeed safety devices.

iunother objectot my invention is to provide an arrangemem; torautomatically dis- "--..iunecting the supply circuit from themultivoltage load circuit without disconnecting an of the balancer sets,which are in oper- 2'. from the multi-voltage load circuit, when apredetermined abnormal condition such as an overload occurs,.and fordisconnecting all of the balance! sets from the load circuit when thevoltage thereof has subsequently decreased below a predetermined Value.

Serial No. 713,614.

Another object of my invention is to provide an arrangement whereby assoon as all of the balanccr sets have been disconnected frommulti-voltage load circuit in response to an aonormal condition on oneof the balancer sets, all of these balancer sets, except the disabledone, are again automatically started and connected to the load circuit.

My invention will be better understood from the following descriptionwhen taken in connection with the single figure of the accompanyingdiagrammatic drawing and its scope will be pointed out in the appendedclaims.

Referring to the drawing, 1 and 2 represent respectively the positivebusses of a direct current supply circuit and the main circuit of amulti-voltage direct current load circuit which are arranged to beconnected together when the circuit breakers 3 and 4 are closed. Thenegative bus 5 is common to both circuits. 6 and 7 represent twobalancer sets which are arranged to maintain the voltage constantbetween the intermediate busses 8, 9 and 10 and the main positive andnegative busses 2 and 5 of the multi-voltage load circuit. Each balancerset consists of four units the rotors of which are mechanicallyconnected together. The armature windings of the units of each set areelectrically connected in series and are arranged to be connected acrossthe supply circuit 1-5 when the circuit breakers 11 and 12 associatedtherewith, and the circuit breaker 3, which is common to both balancersets, are closed. The connections between the adjacent armature windingsof the units of each set are arranged to be connected to theintermediate busses of the load circuits 8, 9 and 10 so that one unit ofeach set is connected across each low voltage circuit of themulti-voltage load circuit. As shown in the drawing, three circuitbreakers 13", 13* and 13 are associated. with each set for accomplishingthis result. The circuit breakers 13 13 and 13 associated with thebalancer set 6 are arranged respectively to connect the intermediate bus8 to the common connection between the armature windings of the units 6and 6 to connect the in termediate bus 9 to the common connectionbetween the armature winding of the units 6 and 6,andto connect theintermediate bus 10 to the common connection between the armaturewindings of the units 6 and 6.

The circuit breakers 13, 13 and l asso ciated with the balancer set 7are arranged respectively to connect the intermediate bus 8 to thecommon connection between" the armature windings of the units 7 and 7 toconnect the intermediate bus 9 to the common connection between} thearmature windings of the units 7* and 7 and to connect the intermediatebus 10 to the common connection between the-armature windings of theunits 7 and 7 'l heret'ore, it will be observed that when the commoncircuit breakers S and t are closed and the circuit breahersll, 12, 1313 and 18 of one of the balancer sets are closed, the respective set isoperative in a manner well known in the art to maintain constant thevoltages across theintermediate circuits of the multi-voltageload'circuit;

W hen both of the halsncer sets are oper sting in parallel it desirableto maintain the load on the two sets substantially equal. Therefore theequalizer husses 15 16, 17 and 18 are provided respectively for theunits 6 and W, the unitsfi and 7 the units 6 end 7 and the 'units 6 and7 of the two balancer sets. The circuit breakers 20, 20, 20 and 20 areprovided with each setto establish the connection between the four unitsthereof and the respective" equalizer busses.

Each halancerset is provided with the shunt field winding 2a", 22, and22; one for each unit thereo The shnntfield windings oi"? each set aresuccessively connected in series in aperm-encn-tly closed circuit whichalso includes the su cessively con.- nected armature windings of thesame set. By having he shunt tield windings and the armature windingspermane tlyv connected together in this manner there is no danger of theset running'awey due to the field circhit being opened. before thearmature circuit opened while the set is being; shut down.

each master switch of? the connect t assoc ed balancer set to the supcircuit l5 with suitable current limiting means 111 s es therewith toprevent an em sweet 1,2 current iiOWlDgE-TtllTOllfZli the set during;starting." Automatic switcling nieo'ns'are provided for decreesingrthecurrent limiting ineansas the speediot the set incre; er until the'set'has reached its i'xormal. speed when the? intermediate bus iiit breakrs-13" 13 andli and the equalizer bus circuit breakers 20 20 20 and 20thereof are closed. Afterthe intern'iediate bus circuit breakers 13*, 13and 13 are closcth the main circuit breaker 4i, which is ccmn'ion to allthe halancer sets, is closed it it. has not already been closed by thestarting of another one of the sets.

l rder to simplify the drz iwing, I have detail only the controlapparatus i irg shutting down and protecting ancer set 6 since thecontrol apparaisted with the balancer set '7, may

the bahncer set 6.

As shown in the drawing, the balencer set 6 is arrsng'edto be started bythe closing ol' mam 11y operated control switch 30, which completes thecircuitoi": a master r 31 A. similar control switch "and 11." -.r i l 31is provided'tor controlling t perauon ot the balancer set 7. The.o'iaster relay of each set, when energized,

completes the circuits of the time'relays and 33 associatedtherewith;Each time relziy arreuged'to shut down the' associated halt'incer setand prevent it from being. restarted in case itis not connected to theload circuit within a predetermined time atter the starting switch" isclosed. Each time relay ie-arranged to etlect the starting: up ofenother balcincer set in case the associated is notconnected to the loadcircuit within a. definite time after the starting cwitch theretoris-closed or the associated tails while in operation. As shown in thedrawing, the time relay 33 associated with the-balancer set 6 isarranged to etl'ect the starting of the balan'cer set i hut'it isobvious to one skilled in the art that the relay 33'cou1dbe arranged toeliecl: the starting of a. third set (not shown) which would function asan emergency set to take the place of the set 6 when it fails. Theemergency set could also: be placed 1:. the controlct the relayassociated with the set 7.

ch master relay also cfiect's the ener- 'i on of an ass ciatcd roastercontrol-contractor 34-- and the closing of the: common so arrange'l thatthe shunt field windings of the set are connected directly across thecontrol circuit and the armature windings are connected across thecontrol circuit with the resistor 35 and the starting resistors 36 and36 in series therewith. The resistor 35 is provided in the armaturecircuit at this time to allow the shunt field current to build up beforeany appreciable amount of current flows through the armature circuit. Itthus prevents the halancer set from starting until the shunt fieldcurrent has been increased to a predetermined value. The resistor alsoserves as a discharge resistor for the shunt field windings when theset. is shut down.

In order that the set may start rotating soon as the field currentbuilds up to a predetermined value. a relay 37 is connected in serieswith the shunt field windings and is arranged to short circuit theresistor soon as the field current ex cecds a predetermined valu Afterthe relay 37 has operated the armature windings of the set are connectedin series across the supply circuit with only the starting resisters 36and 36 in series therewith so that sutticient current flows through thearmatures to cause the set to start rotating. The series contactors 39and il-O are provided successively to short circuit the startingresistors 36 and 36 as the starting current decreases.

Each halancer set is provided with an overspeed device 44 which isarranged to open the contacts 45 associated therewith when the speed ofthe set exceeds a predetern i ed value. The contacts 45 are arranged inany well known manner so that they have to be reset manually. Theopening of the contacts 45 effects, in a manner hereinafter described,the shutting down of the respective In order to protect each unit ofeach hal aucer set against overloads, an overload responsive device 50is provided in each indi vidual armature circuit.

Each overload responsive device prefer ably consists of a fuse 52 and arelay 63 connected in shuntthereto and arranged so that it does notoperate until after the fuse has blown. Since it desirable to shut downa balancer set only in response to sus tained overload itis necessary toprovide an overload responsive device which has a certain time delay inoperating. As is well. known in the art. a fuse has this particularfeature. Another advanta of the par lar arrangement shown is that theresistance of the armature circuit is not nutterially increased undernormal. operating conditions as would be the case if ordinarytlD'lH-dGlfiYBCl overload relays were used place of the arrangementshown.

Each relay v53 controls contacts in the "lhis circuit is closing circuitof the circuit hrealtcr' so that when any one of the relays is operatedthe circuit breaker is opened to disconnect the control circuit 'r thesupply circuit l-5. Therefore an overload on unit of either set eil'ectsthe disconnection of the supply circuit from all of the sets that are inoperation. These sets however, are arranged in a manner hereinafterdescribed to ren'iain conncted to the load circuit until the vi'iltageacross the r'ruitrol circuit dc reases helow a predetermined value.

The relays .33 associated with each set are also arranged to etl ct thevoperation of a lockout rcla i 51 a :ociated the respective set which isarranged to prevent the set from being startet utter it has shut down.

The operat on of the system shown as fiillows:ll hen both of thebalancer sets are shut down, the control apparatus thereis in the po...on shown in the drawing. Since all of the circuit breakers 3 1, l l, 12,13 le 20 20*, 20 and 20 are with.

uit and each balancer set is dis iii the supply and load circuits 16, 1%

and tron'i the equalizer busses lo, and 18.

lVhen it is necessary to put one of the balancer sets into operation,the starting switch associated therewith closet. It tl e halancer set 6is one to be started, the av: ch 30 is closed. whereas it the halancerset 7 is one to he star the switch 30 is closed.

For the i --pose of t description it will be assumed that the switch 30is closed to effect the starting of the balancer set 6.

The closing of the contacts ot' the switch 30 connects the coil of themaster relay 31 across the supply circuit 15 tl the relay 31 operatesand closes its contacts and The closing of the contacts 56 CORP. pletesa circuit for the time re S2 and n0 Oi)- lroui. the positive bus 1 otthe supply circuit. through the contacts 56 of the relay 31. coils oithe time 32 and 33 in parallel, eoi'itacts 58. 58" and :38

of the intermediate bus circuit breakers 13'', 13" and 13 in parallel tothe negative hus 5. Both of these time rola vs begin to time.

The closing of the co-tacts 56 also couretes a circuit for the cl coiloi the c r- Tl'iis circuit is from. the

cuit breaker 3. positive bus 1 through the contacts 54 of the relay 31.conductor 59. contacts co the relays of both halancer sets in closingcoil of the circuit tacts 61 on the break 1' a to the u 7 The closing ofthe circuit lei-ear tive bus 0. cr 3 connects the posi we supply bus tothe positive bus 38 of the control circuit It will observed that thecirc- .it ot' thethe control circuitclosing-coil of'the circuit breaker3 is also arranged to-he completed by the contacts 56. of the relay 31which are connected in shunt to the contacts 56. Therefore, the circuitbreaker 3 is arranged to be closed to energize the control circuit 38whenever either set is started.

When the circuit breaker 3 closes, the closing of the auxiliary contacts63 thereof shunts the contacts 61 of the circuit breaker 4 so that thecircuit of the coil 01": the circuit breaker 3 remains energized alterthe circuit bretl-Ier l closes. With this arrangement, it is possible toclose the circuit breaker 3 only when the circuit breaker is open.Therefore when the circuit breaker 5 is opened, in a manner hereinafterdescribed, to disconnect all of the sets that are in up oration from thesupply circuit when one o" the sets fails, the circuit breaker cannot beclosed to effect the starting up of another set until all of the sets lbeen discou nected from the load circuit by the opening of the circuitbreaker Under the above mentioned conditions, the circuit breaker t isarranged to remain closed in a manner hereinafter described until thevoltageacross the control circuit, which, so long as the circuit breakerl remains closed, is the same as the Voltage across the load circuit2--5, decreases below a predetermined value.

The closing of the contacts 57 of the masster relay 31 completes acircuit for the master contactor 34; associated with the set 6. Thiscircuit is from the positive bus 38 of the control circuit, through thecontacts 57 of the master relay 31, coil of the contactor 34, contacts63 of the time relay 32, contacts (Set of the lockout relay 51,associated with the set 6, contacts of the overspeed switch to thenegative bus 5. The cloship; oi? the auxiliary contacts of the contactor3-icloses a circuit through the contacts 66 of the startingswitch 30which is in shunt to the contacts of the master relay 31 so that in casethe relay 31 fails, he circuit 01 the contactor 3 remains closed afterthe relay 31 opens its contacts The closing ot the main contacts 67 ofthe contac-tor 34lcompletes the circuit of the closing coils of thecircuit breakers 11 and 12 to connect the set 6 across the controlcircuit 385. This circuit is from the positive bus 38 of the controlcircuit, through the contacts 6'? of the contactor 3 1, coils of thecircuit bre hers 11 and 12 in parallel, to the negative bus 5. l

When the circuit breakers 11 and 12 close, the shunt fields 22 22*, 22,and 9,2 are connected in series-with the relay 3? across 5, and thearmature windings, the series field windings 23 23, 23 and 23 of thefour units of the set, the resistors 35, 36 and and the coil of thesture 3 e e e llilet nseries series across the control circuit 33--5.Due to the high resistance of the resistor 35, however, the set does notstart rotating nor does he series contaetor 39 close its contacts. 1

V7 hen the field current has reached a pre determined Value the relayoperates and closes its contacts 68 and 69. The closing of the contacts68 short circuits the resistor so that the armature windings of thebalancer set are connected across the control circuit with the startingresistors 36 and 36 and the series contact-or 39 in series therewith.The rush of currentthrough the series contactor 39, when the resistor 35is short circuited, does not caus it to close its contacts 70. When,however, the starrins' current has decreased to a predetermined value,the contactor 39 closes its contacts thereby completing a shunt circuaround the starting resistor 36. This shunt circuit includes the coil ofthe series centactor e0. l l hen starting current de creases l'elowanother predetermined value the series contactor 4:0 operates to closeits contact Y1, thereby short circuiting both oi the rotors 36 and andalso the coil. of the series contactor 39. Therefore the closing of theseries eontactor 20 connects the tour armature windings of the belancerset directly across the control circuit The series contactor a0 is alsoarranged to close the contacts 72 which, when closed, completes thecircuits of the intermediate bus circuit breakers 13 13 and 13 and theequalizer circuit breakers 20, 20 20 and 20. The circuits for thesecircuit breakers are from the positive bus 38 of the control circuit,through the contacts 67 of the contactor 34;, contacts 69 of the fieldrelay 3?, contacts 72 of the series contactor 40, then in parallelthrough the coils oi the circuit breakers 13 13 13 20, 20 20 20, to thenegative bus 5.

The closing off auniliar contacts M 74: and 74c of the circuit breakers3, 13 and 13 completes the circuit of the closing coil of thecircuitbrcaker 4-. to connect the positive bus 2 of the load ircuit tothe positive bus 38 of control circuit. This circuit of the closing coilis from the positive bus oi the control circuit through the contacts Weof tl e circuit breaker 13, contacts 74;" of the circuit breaker 13contaicts7 1 ot the circuit breaker 1.3, closing coil of the circuitbreaker 4;, to the negative bus 5. The closing of the circuit breaker atC0111 pletes the connection of theset to the multivoltage load circuitso that all of the busses of the multi-voltage load circuit are nowenergized.

l ien the intermediate bus circuit breale ers 13 13 and 1" are closedthe opening of their respective contacts 53, 58 and 58 iiiterrupts theheretet re- (leeches si /ultefor the time relays 32 and 33 so that theserelays are prevented from operatin hen it is desired to shut thebalancer set 6 down, under normal conditions, the starting switchthereof is opened so that the master relay Si is deenergized. Theopening of the contacts 66 of the hand switch deenergizes the contactor34 which, by opening its contacts 67, opens the circuits of theclosii'ig coils of the circuit breakers 11, 12, 13, 13 13, 20", 20, and20 to disconnectthe balancer set from all of the busses. As the se;slows down, the field current decreases so that the field relay 37 opensthe short circuit around the resistor which acts as a dischargeresistor. The series contactor opens to remove the short circuit aroundthe starting resistors 36 and 36 when the circuit breakers 11 and 12open. If the balancer set 7 is not in operation when the switch 30 isopen, the opening of the contacts 56 of the master relay associatedtherewith deenergizes the coil of the circuit breaker 3, which in turndeenergizes the coil of the circuit breaker a so that all of the ontrolapparatus is restored to the position shown in the drawin If, however,the set 7 is in operation when the switch 30 is opened, the circuit ofthe closing coil of the circuit breaker 3 remains completed through thecontacts 56 of the master relay 30 and the circuit of the closing coilof the circuit breaker 4 remains completed through the auxiliarycontacts 74: 74" and 74 on the in termediate bus circuit breakers 13, 13and 13 associated with the set 7.

In the balancer set 6 fails to complete its starting operation within apredetermined time after the starting switch 30 thereof is closed, thetimerelays 32 and 33 have time to complete their operation before theintermediate bus circuit breakers i3, 13" and 13 are closed. The timerelay :3 by opening its contacts 63, opens the heretofore describedcircuit of the master contactor 3i so that the balancer set 6 is shutdown. The relay 32 is made so that its contacts have to be reset by handafter they have opened. Therefore, the balancer set 6 cannot berestarted until after an in specter or some other person has reset therelay 32.

The contacts 76 of the time relay 33 are winnected in the circuit of themaster relay of another balancer set so that this other set is startedautomatically when the time relay 33 closes its contacts 76. As show-nin the drawing, the contacts 76 are connected in parallel with thecontacts of the starting switch 30 of the balancer set 7 so that the set7 is started automatically in case the balancer set fails to start. Itis evident, however, to one skilled in the art, that the contacts 7 6 ofthe time relay 33 associated with the set 6, may be connected in the circuit of the master relay 31 of another set not shown. lVhile I haveshown only two balancer sets it is obvious that my invention not limitedto system having only two sets but is applicable to a system having anydesired number of sets.

In case of an excessive overload on any one of the units of the balancersets 6 and 7, the fuse in armature circuit of the overloaded unit blowsso that the overload relay 53 which is normally connected in shuntaround the fuse receives all of the current flowing through therespective armature winding. This overload relay 53 then opens itscontacts and closes its contacts '78. By opening of its contacts 60 therelay 53 opens the heretofore described circuit of the coil of thecommon circuit breaker 3 so that the positive bus 38 is disconnectedfrom the positive supply bus 1. This allows the voltage of the wholebalancer system to die down as the speed of the balanccr sets decreasessince the supply circuit is disconnected from the load circuit.

S nce the closing coil circuits of the circuit eaker i and all of thecircuit breakers f 3 13 20, 20', 20 and 20 are connected acr the controlcircuit 38-5, it is evident that so long as these circuits remain closedand the voltage across the control circuit remains above a predeterminedvalue the circuitbreakers will remain closed. Therefore since theoverload relays 53 are not arranged to open any of these closingcircuits all of the balancer sets, which are in operation when anoverload occurs, remain connected to the load circuit after the circuitbreaker 3 opens until the voltage across the control circuits 38 5,which is connected to the main circuit 2-5 of the load circuit by thecircuit breaker at, decreases below a predetermined value.

l-Vheu the circuit breaker 4 opens so that its auxiliary contacts 61 areclosed and the current through the armature winding of the overloadedunit has decreased suflicient ly to allow its overload relay 33 to closeits contacts 60, the heretofore described circuit for the closing coilof the circuit breaker 3 is completed through the contacts 60 of all theoverload relays 53 and the contacts of the master relays which may beenergiaed It will be observed that it is necessary tl the contacts 60 ofall of the overload rcla s 53 must be closed, and the circuit breakersmust be open before the circuit breaker 3 can reclose. If more than oneset is in operation when the fault occurs, the set in which the faultdoes not occur, is started up and connected to the load circuit in themanner heretofore described as soon as the circuit breaker 3 recloses.The set that causes the shut down, however, is prevented from startingup after the circuit brea. er t opens, in the following manner.

The. closing of the contacts 78 of the overload relay that is operatedby the overload comp'letes a circuit for theloclr-outrelay 51 or" therespective set. lhis circuit is troin'the positive sijipply bus throughthe coil of the lock-out relay 51, contacts 78 of the operated overloadrel; y 53 to the negative bus Since the' lockout relay 51 has to bereset by hand, the opening o'fits contacts which are in the heretoforetraced circuit of the n: aster contactor-Sd, prevents thebalancerset'trmrnbeing started again until it has been inspect-ed.

When the'circuit breakers 13 13 and 13 or the set on which the overloadoc 'urred open, the heretofore described circuit for the time 32 "and iscompleted. Since the lock-out relay 51 associated with the particularset operates in the manner above described, to prevent the set frombestartechit will be evident that the time relays associated therewithwill effect the automatic starting up of another set, to replace thedisabled set.

It for any reason thespeed of a balancer set should increase above thesetting of the overspeed switch a4; associated therewith, this switchopens its associated contacts 45, thereby deenergizing the mastercontactor 3% of the set. The opening of the master contactor opens thecircuits of the coils of circuit breaker 11, 12, 13 13- 13, 20, 20", 20and 20 of the set so that the set is con pletely disconnected tromtheload circuit. The opening of the intermediate bus circuit breakers-13,113 ,'and13 efiect'in a manner heretofore described the opening-of thecircuit breaker 4, if no other set is in operation, and the operation ofthe time relays 32 and 33 to lock out the set and to effect thestarting" of another set.

In case the field circuit of a 'balancer set should fail, the fieldrelay 37 opens its contacts 68 and 69. The opening); of the contacts68i11ft-$ the resistor 35 in'series with the set. The resistance of theresistor '35 is so high that the current through the armature windingsot-thesct is reduced to a very small value. The opening of the contacts69 opens the circuits of the closing coils of the intermediate buscircuit breakers 13 13 and 13 As heretofore described the open ing ofthese intermediz'ite bus circuit breakers effects the shutting down andlocking out of the set that has failed and the start ins: of anotherset.

While I have, in accordance with the patent statutes, shown anddescribed my invention as applied to a particular system and asembodying various devices diagrammatically indicated, changes andmodifications 'will be obvious to those skilled in the" art, and Itherefore aim in the appended claims to cover all such changes andmodifications as namo electric machines having their rotors fall withinthe true spirit and scope of my inve ition.

Vhat'I claim as new and desire to secure by plotters Patent ot theUnited States is 1. In combination, a direct current supply circuit, amulti-voltage direct current load circuit, a balancer setarranged tosupply the intermediate circuits of said multi-voltage circuit,automatic switching means for connecting saidbalancer set/to said supplycircult to effect the starting of said set, means for ettectingtheoperation of said automatic switching means, and automatic switchingmeans operative in response to the starti of said balancer set toconnect said balancer set tothe intermediate circuits otsaidmultivoltag'e load circuit.

2. In combination, a direct current supply circuit, a multi-voltagedirect current load. circuit, abalancer set arranged to supply theintermediate circuits of :said multi-voltage circuit comprising aplurality of dynamo electric machines having their rotors mechanicallyconnected together and their armature windings electrically connected inseries, current limiting means, switching means arranged to connect saidarmature windings and said current limiting means in series across saidsupply circuit to start said set, automatic switching means operative inresponse to the starting current tor decreasing the amount of currentlimiting; means in series with the armature windings, and

switching means for automatically connecting said armature windingsacross different intermediate circuits of said multi-voltage loadcircuit when said current limiting means has been decreased apredetermined amount.

3. In combination, a direct current supply circuit, a multi-voltagedirect current load circuit, a balancer set arranged to supply theintermediate circuits of said multi-voltage circuit, automatic switchingmeans for connecting said set to said supply circuit and for controllingthe connection thereto to ettect the starting of said set, means foreffecting the operation of said automatic switch ing means, andswitching means for automatically effecting the connection 01" saidbalancer set to the intermediate conductors of said multi-voltagecircuit and the subsequent connection of said supply circuit to the mainconductors oi said multi-voltage load circuit after said set has beenstarted.

4. In combination, a direct current supply circuit, a multi-voltagedirect current load circuit, a balancer set arranged to supply theintermediate circuits of said inulti-voltage load circuit comprisinga'plurality ot dymechanically connected together and their armaturewindings electrically connected in series, current limiting means,switching means arranged to connect said armature windings and saidcurrent limiting means in series across said supply circuit to startsaid set, automatic switching means operative in response to thestarting current for decreasing the amount of current limiting means inseries with the armature windings, and switchi g means operativeautomatically when said current limiting means has been decreased apredetermined amount for e1- tecting the connection of said balancer setto the intermediate conductors of said multivoltage circuit and theconnection of said supply circuitto the main conductors of saidmulti-voltage load circuit.

In combination, a direct current supply circuit, a n'iult-i-voltagedirect current load circuit, a balancer set arranged to supply theintermediate circuits of said multi-voltage circuit, automatic switchingmeans for connecting said set to said supply Cll'Cllit and forcontrolling the connection thereto to eiiect the starting of said set,means arranged to efi'ect the operation of said automatic switchingmeans, switching means operative in response to a predeterminedcondition of said automatic switching means for eii'ecting theconnections between said balancer set and the intermediate conductors ofsaid multivoltage load circuit, and means operative in response to apredetermined condition of said last mentioned switching means forestablishing the connection between said supply circuit and the mainconductors of said multi-yoltage load circuit.

6. In combination, a direct current supply circuit, multi-voltage directcurrent load circuit, a balancer set arranged to supply the intermediatecircuits of said multi-voltage circuit, automatic switching means forconnecting said set to said supply circuit and for controlli heconnection thereto to eii'cct the st of said set, means arranged toeffect the operation of said unto rustic switch N means, switching meansoperative in r use to a predetermined condition of said automatic SW foreii'ccting the connections bet-seen said balanccr set and theintermediate conductors of said nuilti-voltage load ci cuit, andautomatic switching means operative in respouse to the establishment oft] connections between said set and the intermediate conductors of saidload circuit for effecting the connection between said supply rcuitandthe main conductors o rid mu 'tE-YOllage load circuit.

7. In combiinuiion, a direct ran-rent supply circuit, a multi-voltageirect current load circuit, a plurality ct b leer set-'1 arranged tosupply the intermediate circuits oi said inulti-voltr -30 load circuit,each balancer set comprising plurality of dynamo electric machii :1these rotors mechanically ciated with each set and operative in response to a predetermined condition of the automatic switching means ofthe respective set for effecting the connection between the respectiveset and the equalizer conductors.

8. In combination, a direct current supply circuit, a multivoltagedirect current load circuit, a balance]? set for supplying theintermediate circuits of said multi-voltage load circuit, switchingmeans for connecting said supply circuit to the main circuit of saidmulti-voltage load circuit, switching means for connecting said balancerset across the intermediate circuits of said load circuit,electroresponsive means operative in response to the voltage across themain circuit of said load circuit for controlling said last mentionedswitching means, and overload rcsponsive means for controlling theopening of said first mentioned means whereby the occurrence of anoverload causes said supply circuit to be disconnected from the maincir-- cuitof said load circuit and said balancer set remains connectedacross the intermediate circuits of the load circuit until the voltageacross the main circuit thereof has decreased below a predeterminedvalue.

9. In combination, a direct current supply circuit, a multi-voltagedirect current load circuit, a balanc-er set for supplying the intermediate circuits of said multi-voltage load circuit comprising aplurality of dynamo electric machines having their rotors inc--chanic-ally connected t ether and their armature windings electricallycon ed in series, switching means for count wing said supply circuit tothe main circuit or saic multi-voltage load circuit, switching 1 forconnecting said set to the load ciriii. and overload responsve meanscom; cted in the armature circuit of said set tor con trolling said.first mentioned switching means.

10. In con'ibination a direct current sup ply circuit, a multi-voltagedirect current load circuit. a balancer set tor sumilying theintermediate circuits of said u'iulti-voltage load circuit comprisingplurality of dynan'io electric machines having their rotors mechanicallyconnected together and their armature windings electrically connected inseries, electroresponsive switcln ing means for connecting said supplycircuit to the main circuit of said multi-voltage load circuit,switching means for connecting said set to the load circuit, a fuse inseries With ill) Ill

field current for conn or each armaturewinding oi? said set, arelayconnected in shunt around each and arranged so that it does not operateuntil its respective tuse has blown, and a circuit for saidelectroresponsive switching means con trolled by said relays,

11. in combination, a ti 1; plycircuit,amulti-voltzwe ect current loadcircuit, a balancer set 0;- St mi 13 the intermediate circuits or saidinultiroltage load circuit comprising a plurality of dyna- 1P0 electricnachines having}; their rotors mechanically connectedtogether and theirarmature windii electrically connected series, shunt-field winding t reach one of said machines, a 3' ar'anged to connector 1d w and saidresistor in series a ply circuit and to co inec; ill field windings inseries circuit, and means i re *t ciurrent supcross l J l I ,ing'tl'ieco of said resistor in the armature circuit said'sct.

12. In combination, direct current ply circuit, a multiwolt loadcircuit. a halancer ct the intermediate circuits or age load circuitcomgrising dynamo electric machines havn s mechanically connectedtogether and lllil armature Windin electrically connected. in series,field windings for said i'nacliines, a control circuit, sivitchin meansfor connecting said supply circuit to said control circuit, switching; mans arranged to connect said armature w ndings and said field windingsacross said control circuitto eii'cct the starting of set, switching; inms ranged to connect'eacli armature ii acrdss a different intern'iediatecircuit or s- 7. load circuit, and overload responsive 1.16 forcontrolling the operation of said in sntioned switching; means 13, incombination, ac i nly circui a multi-Voltage i load cir 11 1t, balance]?set for so lltelfl etlliltfi circuits of said in load circuit comp isinga rdurality of dyi mo electric machines he: their rot: mechanicallyconnected together and their armature windings electrically connected.in series, iield windings for said machines, a control circuit, stchingr ineai'is tor connecting said supnly circuit to said controlcircuit, switching means arranged to connect said armature windings andsaid field windinns across said control circuit to eti ct the starting01? said set, switching; means arranged to connect each n across adiiierent intermediate circuit of said load circuit, means operative inresponse to the voltage across the control c1r cuit for controlling;said two last mentioned switching means, and overload responsive uea-usin the circuit oteach armature Winding for controlling said firstmentioned switching means.

ll. In combination. -a direct current supply circuit, a nuilti roltagedirect current load circuit, a halancer set for supplyingtheintermediate circuits oi? said multi-voltage-load circuit comprisinga plurality of shunt dynamo electricinachines having their rotorsinechanicaly connected together, a permanently closed circuitharing allof the armaturewindings ot' saidnlnachines and all of the shunt fieldwindings of said niachincs successively arranged therein, automaticswitching); means lior connecting said closed circuit to said. siu'mlrcircuit and for controlling;theconnection thereto whereby said lieldwindings and said armature windings are 'onnectcd in parallelacrosscircuit to ell ect the starting 01' sivitchin means -for, conne ctin-gar Wind'iig across a different idiatecircuit or saidload-ehrc lit.

1 coml; inat.ion, a direct current supgz'e direct current n to torsiuvplyingthe of said nmlti-voltage prism-o a plurality of shuntmachines lltWlnQ thenro- ;ly closed circuit having all of the arl oisaidn schines and all oi l -1 it zieid windings of said machines rrelyaranyged therein, a control circuit. switching" means for connectingsaid su iiply circuit to saidcontrol circuit, switching imans forconnecting said closed circuit to said control circuit- Whereby'saidlield windings and said armature windingsiare connected in parallelacross said control circuit, ant switching means arranged'to connectsaid control circuit across the main .iid load circuit and eacharmaacross a different intermei said load circuit. combination a directcurrent sup- 1 o :it, a mul iwoltage direct current load (Ll unit, ahalaneer set tor supplying the intermediate circuits ot-saidmulti-voltaoe load circuit con'iprising a plurality of dyname electricma-h-ines havingtheir rotors mechanically connected together. aperinancntly closed circuit having all of the arm; ture windings of-saidmachinesand all of the shunt field windings of said ma hinessuccessircly arranged therein, acontrol circuit,

switching;- means for connecting said suonlv circu t to said controlcircuit, switching means for connecting sa'd closed circuit to itl'Olcircuit whereby said lield Windings ant. said armature windings areconnected in parallel across said control circuit, switching meansarraneed to connect said control circuit across the main circuit or"said load circuit and each armature Winding across said coi Ly CO1nected together, a per- I ill) lift

a different intern'iediate circuit of said load circuit, meansresponsive to the voltage across said control circuit for controllingthe opening of said last two mentioned switching means, a fuse in thecircuit oi? each armature winding, a relay connected in shunt aroundeach fuse and arranged so that it does not operate until said fuse hasblown, and means controlled by said relays for effecting the opening ofsaid first mentioned switching means when any one of said fuses blows.

17. In combination, a direct current supply circuit, a multi-voltagedirect current load circuit, a balancer set for supplying theintermediate circuits of said multi-voltage circuit comprising aplurality of shunt dynamo electric machines having their rotorsmechanically connected together, current limiting means, a permanentlyclosed circuit having the shunt field windings and the armature windingsof said machine successively connected therein and including saidcurrent limiting means, means for connecting said closed circuit to saidsupply circuit whereby the shunt field windings are connected in seriesdirectly across the supply circuit and the armature winding and thecurrent limiting means are connected in series across the supplycircuit, means for decreasing the amount of current limiting means inseries with said armature windings, and means for connecting saidbalancer set to said multi-voltage circuit.

18. In combination, a direct current supply circuit, a multi-voltagedirect current load circuit, a balancer set for supplying theintermediate circuits of said multi-voltage circuit comprising aplurality of shunt dynamo electric machines having their rotorsmechanically connected together, current limiting means, a permanentlyclosed circuit having the shunt field windings and the armature windingsof said machine successively connected therein and including saidcurrent limiting means, means for etl'ecting the starting of said setarranged to connect said closed circuit to said supply circuit wherebyall of the shunt field windings are connected in series across thesupply circuit and the armature windings and the current limiting meansare connected in series across the supply circuit, automatic switchingmeans operative in response to the starting current through saidarmature windings for decreasing the amount of current limiting means inseries with the armature windings, and switching means for automaticallyI connecting said armature windings across different intermediatecircuits 'of said multi-volta'ge load circuit -when said currentlimiting means has been decreased. a predetermined amount.

19. Incombination, a direct current supply circuit, a multi-voltage.direct current load circuit, a balancer set for supplying saidmulti-voltage load circuit, automatic switching means for connectingsaid set to said supply circuit and for controlling the connectionthereto to eflect the starting of the set, other switching means forautomatically connecting said set to the load cir cuit when the startingoperation has been completed, starting means adapted to be operated toeffect the operation of said automatic switching means, and means fordisconnecting said set from said supply circuit if said startingoperation is not completed within a predetermined time.

20. In combination, a direct current sup ply circuit, a multi-voltagedirect current load circuit, a balancer set for supplying saidmulti-voltage load circuit, automatic switching means for connectingsaid set to said supply circuit and for controlling the connectionthereto to effect the starting of the set, other switching means forautomatically connecting said set to the load circuit when the startingoperation has been completed, starting means arranged to be operated toeffect the operation of said automatic switching means, a time relayarranged to effect the disconnection of said set from said supplycircuit, a circuit for said relay arranged to be completed in responseto the operation of said starting means, and contacts in said relaycircuit controlled by said other switching means whereby said relaycircuit is opened before said time relay effects the disconnection ofthe set from the supply circuit if the starting operation is completedwithin a predetermined time.

21. In combination, a direct current supply circuit, a multi-voltagedirect current load circuit, a plurality of balancer sets for supplyingsaid multi-voltage load circuit, automatic switching means associatedwith each set for connecting the respective set to the supply circuitand for controlling the connection thereto to effect the starting of theset, other switching means associated with each set for automaticallyeffecting the connection thereof to the load circuitwhen the startingoperation thereof has been completed, starting means arranged to be operated to effect the operation of one of said automatic switching means tostart one of said balancer sets, and means for effecting the operationof another of said automatic switching means to start another of saidbalancer sets it the set which is controlled by said first mentionedstarting means is not connected to the load circuit within apredetermined time after it has been started.

22. In combination, adirect current supply circuit, a multi-voltagedirect current load circuit, a. plurality of balancer sets for supplyingsaid multi-voltage load circuit,

ran d tab ar automatic switching; means associ" i eachsetior connectingthe respective set to the supply circuit and for controlling theconnection thereto to effect the star" the set, other switching; meansassociated with each set for automatically effecting the connectionsthereof to the load circuit when the starting' operation has beencompleted, starting means arranged to he operated to effect theoperation of one of said autcn'iatic switching means to start one ofsaid halancer sets, a time relay arranged to eti'ect the ing of anotherone of said automatic switching means, a circuit for said time relayarranged to he con' pl'eted in resrmnse the operation of said startingmeans, and contacts in the circuit of said time relay controlled by thesaid other switching means associated with the balancer set-which isarranged to he started by the operation oi? saidstarting means.

23. in combination, .1 t ply circuit, a multi roit ect current loadcircuit, a plurality oi hale cer sets for supplying said multi-vo tageload circuit, a control circuit, automatic switchin means associatedwith each set connecting: the respective set to the control circuit andfor controlling the connections thereto to Kit the starting of the setand tor connecting the respective set to the load circuit, r meanassociated with each set arranged to be operated to etiect the operationof the automatic switching means 01" the respective set, and commonswitching means for connecting said supply circuit to said controlcircuit arranged to be operated automatically in response to theoperation of any one of said starting means.

24. In combination, a direct current sup ply circuit, a multi-voltsgedirect current load circuit, a plurality of halancer sets for supplyingsaid multi-voltage load circuit, each balancer set having-the rotorsthereol mechanically connected together and the armature windingsthereof electrically connected in series, a, control'circuit, automaticswitching means associated with each set for connecting. theseries-connected armature windings of the respective set acr ss saidcontrol circuit to effect the'starting of the est and for connecting thecommon connec tions'hetw veen the-adjacentarmature wind ings of therespective set to the intermediate conductors of the inulti-voltag eiota circuitafter the has been started, starting means associatedwith'each'setarranged to he open ated to" effect" the' operationot theautomatic witching means oithe associated set, switching means forconnecting said supplycircuit to said control circuit, and a commonsivitchlug means tor connecting thecontrolcircuit to'tlie mi hconductorsof the'loadcircuitan creases-yin sponse to the operation ofany one of said automatic switching means.

25. In combination, a direct current supply circuit, a multi-voitag'edirect current load circuit, a plurality of balancer sets for supplyingsaid multi-voltage load circuit, each halancer set having the rotorsthereof mechanically connected together and the armature windingsthereof electrically connected in series, a control circuit, automaticswitching means associated with each set for connecting theseries-connected a 'i'nature windings of the respectiv set across saidcontrol circuit to effect the starting of the set and for connecting thecommon connec tions between the adjacent armature windings of therespective. set to the intermediate conductors of the muli'voltage loadcircuit afterthe set has been started, starting means associated witheach set arranged to he opereted to effect the operation ot theautomatic switching means of the associated set, a common switchingmeans for connecting said supply circuit to said control circuitarranged to be operated automatically in response to the operation ofany one of said starting means, and a common switching means forconnecting the control circuit to the main conductors of the loadcircuit arranged to be operated automatical y in response to theoperation otany one of said automatic switching; means.

In combination, a direct current supply circui a multi-voltage directcurrent load circuit. z t-plurality of halancer set-search setcomprising a plurality of" dynan'io-eler trio machines having theirrotors mechanically connected together andtheir arn'iature windingselectrically connected in series, a control circuit, switching meansassociated with each set for connecting the series-connected armaturewindings of the respective set acrcssseid control circuit and 51connecting the common connections between ad- 7 re windings of therespective set to the intermediate conductors of the inultiwoltan'e loadcircuit, switching means tor connecting said control circuit to the mainconductors of the load circuit, means responsive to the voltage acrosssaid con: trol circuit for contrclling the opening of hoth of seid s; 'whing means, switching means for connect said supply circuit to thecontrol ciroui an overload responsiv means associated with eachmachineof all of the haiancer sets-for controlling the opening of said lastmentions switchi means.

:21. In combination, a direct current supply circuit. a nulti-voltagedirect current load circuit, a plurality of balancei' sets, each setcomprising a plurality of dynamo electric machines havingtheirrotorsmechanically connected together and-their armature wir rigs electricallyconnected in series, a control circuit, switching means as sociated witheach set for connecting the series-connected armature windings of therespective. set across said control circuit and for connecting thecommon connections between adjacent arn'iature windings of therespective set to the intermediate conductors of the multi-voltage loadcircuit, switching means for connecting said control circuit to the mainconductors of the load circuit, means responsive to the voltage acrosssaid control circuit for controlling the opening of both ot saidswitching means, electrore sponsive means for connecting said supplycircuit to the control circuit, a circuit for said electroresponsivemeans, a fuse in the armature circuit of each dynamo electric machine ofeach balancer set, a relay in shunt around each fuse, and contacts inthe circuit of said electroresponsive means controlled by said relays.

28. In combination, a direct current sup ply circuit, a multi-voltagedirect current load circuit, a plurality of balancer sets for supplyingsaid multi-voltage load circuit, automatic switching means associatedwith each set for effecting the starting of the respective set and theconnection thereof to the i'nulti-voltage load circuit, means associatedwith each set adapted to be operated to effect the operation of theautomaticswitching means associated therewith, means operative inresponse to an overload on any one of the halancer sets to disconnectthrsupply circuit from all of the balancer sets in operation andsubsequently to disconnect all of the balancer sets from the loadcircuit when the voltage thereof has decreased below a predetermined"alue, means responsive to an overload on any one set for preventing thesubsequent operation of the automatic switching means associated therewith. and means operative when all of the sets have been disconnectedfrom the load circuit in response to an overload on one of the sets toeffect the operation of the auto" matic switching means of all of thesets which were in operation when the overload occurred except the onewhich was overloaded.

29. In combination, a direct current supply circuit, a multi-voltagedirect current load circuit, a plurality of balancer sets for supplyingsaid multi-voltage load circuit, automatic switching means associatedwith. each set for efifecting the starting of the respective set and theconnection thereof to the multi-voltage load circuit, means associatedwith each set adapted to be operated to effect the operation of theautomatic switching means associated therewith, means operative inresponse to an overload on one of said balancer sets to disconnect thebalancer set from the supply circuit and subsequently to disconnect thebalancer set from the load circuit when the -voltage thereof de--creases below a predetermined value, means operative in response to anoverload on any one of said balanccr sets for preventing th subsequenoperation of the automatic switching means associated therewith, andmeans operative after said one of said ba-lanccr sets has beendisconnected from the load circuit in response to an overload foreffecting the operation oi the automatic switching are. is associatedwith another one of said plurality of balancer sets.

.00. In courhination. a direct current ply circuit, a multi-voltagedirect current load circuit, a balancer set for supplyin saidmultio'oltage load circuit, electroresponsive means for controlling theconnection between said halancer set and said supply circuit, switchingmeans for connecting said set to said multi-voltage load circuit,overload responsive means, and a circuit for said electroresponsivemeans controlled by said twitching means and said overload responsivemeans.

Si. In con'ibination, a direct current supply circuit, niulti-voltagedirect current load circuit, a balancer setfor supplying saidmulti-voltage load circuit comprising a plurali of dynamo electricmachines ha ing their rotors mechanically connected together and theirarmature windings electrically connected inseries, a control circuit,eloctroresponsive means for connecting 25 d control circuit to saidsupply circuit, switching n'ieans for connecting said halancer set tosaid control. circuit, switching means for connecting said controlcircuit to the main conductors of the multi-voltago load circuit, acircuit for said electroresponsive means, and means controlled by saidlast n'icntioned switching means for preventing the closing of saidcircuit of said electroresponsive means when said control circuit isconnected to the main conductors of said multi-voltago load circuit.

In combination, a direct current sup-' ply circuit, a multiu'oltagedirect current load circ'c" a balancer set for supplying said mult.oltage load circuit comprising a plurality of dynamo electric machineshaving their rotors mechanically connected together and their armaturewindings elec trically connected in series, control circoil,electroresponsive means for connech iug said control circuit to saidsupply circuit. switching means for connecting said halanccr set to saidcontrol circuit, switch ing means for connecting said control circuit tothe main conductors of the multivoltage load circuit, a circuit for saidelectroresponsivc means, and overload responsive means in the armaturecircuit of each machine of said balancer set for controlling saidcircuit of said electroresponsive means.

33. In combination, a direct current suppl circuit, a multi-voltagedirect current load circt: t, a halancer set for supplyingvoltage loadcicuit comprising of dynamic electric 5 .eir roto mechanically connectednd their armature windings elecconnected in series, shunt field windidmachines, switching means for said series-connected armature 10 windings"aid shunt field windings 1 across sa d supply circuit, switching meansiectnp; said balancer set to said load circuit, and means re- 14 r 1. :1rule,- chase sponsiye to rho current through said field t or controllingsaid last mentioned ing s sponsive n cans for connecting said balanccrsetto said inultr'vol age load circuit, a cirsaid elcctroresponsivemeans, and contacts in said circuit of said electroresprmsive meanscontrolled by the current in said field windings.

in combination, a direct current supply circuit, a multi-voltage directcurrent loadv circuit, a balancer set for supplying said m'ulti-voltageload circuit comprising a plinality oi dynamo electric machines haw ingtheir rotors mechanically connected tonether and their armature windingselectricallyconnected in series, shunt field windior said machines,switching means for connecting said series-connected armature windingsand said shunt field windings across said supply circuit,electroresponsive means for connecting said halancer set to r P curt ror1 rachines said inulti-i'oltage load circuit, a circuit forelectroresponsive means, contacts in said circuit of saidelectroresponsive means controlled by the current in said fieldwindings, and. means controlled by said electroresp-onsiye means forcontrolling said switching means.

ac. in con'ihination, a direct current supply circuit, a ilti-yoltageload circuit, a l: sneer set for supplying said multi-volt road circuit,automatic switching m ans for connecting said set to said supply circuitand for controlling the connection thercto to eliectthe starting of saidset, other switching means for automatically connecting said set to theload circuit when tarting operation has been completed, means adapted tobe operated to ell-cc; the operation of said automatic switching means,a time relay arranged to efiect the disconnection of said set from saidsup-1 ply circuit and toprevent the operation of said automaticswitching means, and a circuit for said time relay controlled by saidstarting means and said other switching means.

9?. In combination, a directcurrentsupply circuit, a multi-voltage loadcircuit, a plurality of halancer sets for supplying; said multi-yoltageload circuit, automatic switching means associated with each set forconnecting the respective set to said supply circuit andto said loadcircuit, starting means associated with each set adapted to be operatedto effect the operation oi the automatic switching means associatedtherewith, time relay associated with one of said sets and arranged toeliect the operation of the automatic switching means associated withanother one of said sets, and a circuit for saic time relay controlledhy'thc starting means and the automatic switching means of the set withwhich said relay is associated.

in witness whereof, l have hereunto set my hand this 14th day of May,1924:.

ELMER F. BLISS.

